package problems;

import java.util.ArrayList;
import java.util.List;

import lib.MathLib;

public class Euler011 extends AbstractEuler {
	long[][] grid = {
/*		  0  1  2  3  4  5  6  7  8  9 10 11 12 13 14 15 16 17 18 19 */
/*  0 */{ 8, 2,22,97,38,15, 0,40, 0,75, 4, 5, 7,78,52,12,50,77,91, 8},
/*  1 */{49,49,99,40,17,81,18,57,60,87,17,40,98,43,69,48, 4,56,62, 0},
/*  2 */{81,49,31,73,55,79,14,29,93,71,40,67,53,88,30, 3,49,13,36,65},
/*  3 */{52,70,95,23, 4,60,11,42,69,24,68,56, 1,32,56,71,37, 2,36,91},
/*  4 */{22,31,16,71,51,67,63,89,41,92,36,54,22,40,40,28,66,33,13,80},
/*  5 */{24,47,32,60,99, 3,45, 2,44,75,33,53,78,36,84,20,35,17,12,50},
/*  6 */{32,98,81,28,64,23,67,10,26,38,40,67,59,54,70,66,18,38,64,70},
/*  7 */{67,26,20,68, 2,62,12,20,95,63,94,39,63, 8,40,91,66,49,94,21},
/*  8 */{24,55,58, 5,66,73,99,26,97,17,78,78,96,83,14,88,34,89,63,72},
/*  9 */{21,36,23, 9,75, 0,76,44,20,45,35,14, 0,61,33,97,34,31,33,95},
/* 10 */{78,17,53,28,22,75,31,67,15,94, 3,80, 4,62,16,14, 9,53,56,92},
/* 11 */{16,39, 5,42,96,35,31,47,55,58,88,24, 0,17,54,24,36,29,85,57},
/* 12 */{86,56, 0,48,35,71,89, 7, 5,44,44,37,44,60,21,58,51,54,17,58},
/* 13 */{19,80,81,68, 5,94,47,69,28,73,92,13,86,52,17,77, 4,89,55,40},
/* 14 */{ 4,52, 8,83,97,35,99,16, 7,97,57,32,16,26,26,79,33,27,98,66},
/* 15 */{88,36,68,87,57,62,20,72, 3,46,33,67,46,55,12,32,63,93,53,69},
/* 16 */{ 4,42,16,73,38,25,39,11,24,94,72,18, 8,46,29,32,40,62,76,36},
/* 17 */{20,69,36,41,72,30,23,88,34,62,99,69,82,67,59,85,74, 4,36,16},
/* 18 */{20,73,35,29,78,31,90, 1,74,31,49,71,48,86,81,16,23,57, 5,54},
/* 19 */{ 1,70,54,71,83,51,54,69,16,92,33,48,61,43,52, 1,89,19,67,48}
	};
	
	private static int GRID_SIZE = 20;
	
	@Override
	public Number calculate() {
		Long maxProduct = 0L;		
		
		for (int y = 0; y < GRID_SIZE; y++) {
			for (int x = 0; x < GRID_SIZE; x++) {

				//Horizontal search
				if (x + 4 <= GRID_SIZE) {
					List<Long> line = new ArrayList<Long>();
					
					line.add(grid[y][x]);
					line.add(grid[y][x+1]);
					line.add(grid[y][x+2]);
					line.add(grid[y][x+3]);
					
					Long product = MathLib.getProduct(line);
					if (product > maxProduct) {
						maxProduct = product;
//						System.out.println("new max product of " + line + " found horizontally from [" + x + "," + y + "] as " + product);
					}
				}
				
				
				//Vertical search
				if (y + 4 <= GRID_SIZE) {
					List<Long> line = new ArrayList<Long>();
					
					line.add(grid[y][x]);
					line.add(grid[y+1][x]);
					line.add(grid[y+2][x]);
					line.add(grid[y+3][x]);
					
					Long product = MathLib.getProduct(line);
					if (product > maxProduct) {
						maxProduct = product;
//						System.out.println("new max product of " + line + " found vertically from [" + x + "," + y + "] as " + product);
					}
				}
				
				//Diagonal search "\"
				if (x + 4 <= GRID_SIZE &&
					y + 4 <= GRID_SIZE) {
					List<Long> line = new ArrayList<Long>();
					
					line.add(grid[y][x]);
					line.add(grid[y+1][x+1]);
					line.add(grid[y+2][x+2]);
					line.add(grid[y+3][x+3]);
					
					Long product = MathLib.getProduct(line);
					if (product > maxProduct) {
						maxProduct = product;
//						System.out.println("new max product of " + line + " found diagonally \"\\\" from [" + x + "," + y + "] as " + product);
					}
				}
				
				//Diagonal search "/"
				if (x - 4 >= 0 &&
					y + 4 <= GRID_SIZE) {
					List<Long> line = new ArrayList<Long>();
					
					line.add(grid[y][x]);
					line.add(grid[y+1][x-1]);
					line.add(grid[y+2][x-2]);
					line.add(grid[y+3][x-3]);
					
					Long product = MathLib.getProduct(line);
					if (product > maxProduct) {
						maxProduct = product;
//						System.out.println("new max product of " + line + " found diagonally \"/\" from [" + x + "," + y + "] as " + product);
					}
					
				}
				
			}
		}
		
		return maxProduct;
	}

	@Override
	protected Number getCorrectAnswer() {
		return 70600674L;
	}

}
